The inquest was told Boots sent 60mg tablets to Springbank House Care Home in Chesterfield, where Mrs Devereaux was residing, when it should have sent just 10mg pills 'as a result of human error'.

The mistake was not spotted by the home's staff on multiple further occasions despite stringent rules regarding the administration of controlled drugs, the inquest heard.

Mrs Devereaux died at Chesterfield Royal Hospital on November 30, 2012.

Coroner James Newman ruled 'clear opportunities' to correct the medication error from the start were 'not identified and resulted in an acute morphine overdose that had a clear and primary role in Mrs Devereaux's death'.

Her grieving daughter Sonia, 51, will appear on 'Boots: Pharmacists under Pressure? An Inside Out Special' on BBC1 at 7.30pm. It will be available on the BBC iPlayer after it has aired.

The programme's synopsis states: "Behind the counter at the UK's biggest pharmacy chain, some are worried about workload pressure and patient safety."

According to the BBC, Mrs Devereaux was one of three people to die between May, 2012, and November, 2013, following dispensing errors by Boots.

Several current Boots pharmacists will tell the programme that understaffing could pose a risk to patients.

But Boots insists its pharmacies are not understaffed and it has an industry-leading patient safety record.

Sonia, of Inkersall, said: "I think about my mum every day - I miss her so much.